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  • Adding Solid-State Storage to an Original IBM PC

    14 Aug | 17
    • in Electronics • 
    • in IBM PC • 
    • by Chris Osborn

    After CGA Weekend it became pretty obvious I needed to do something about getting some kind of permanent mass storage installed in my IBM PC. I can't simply add an IDE hard drive controller since the slots are only 8-bit and in general IDE controllers are designed for 286 computers and up which have 16-bit ISA slots. 8-bit SCSI cards are uncommon and ones that can be used to boot from even more so. I've messed around with using the XT-IDE BIOS over serial , but it was very slow. The...

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  • Are you ready for #AppleIIWeekend?

    03 Feb | 17
    • in Electronics • 
    • in Raspberry Pi • 
    • in Apple II • 
    • by Chris Osborn

    The retro computing high score challenge this weekend is a special one! Unlike previous contests which were meant to inspire me to mess with computers in my collection that I'm not very familiar with and know very little about, this contest is about the Apple II which is the one I grew up with. 35 years ago in 1982 my family got an Apple II+ and in 1986 we got a IIgs. In 1990 I even worked on two different Apple IIe emulators for the NeXT computer. Because the Apple II is so special...

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  • Controlling WS2812 RGB LEDs from the ESP32

    19 Nov | 16
    • in ESP32 • 
    • by Chris Osborn

    I've posted my code which uses the RMT peripheral on the ESP32 to control WS2812 RGB LEDs. The LEDs can be controlled from within a task without any flickering because the timing of the pulses is controlled by the RMT peripheral. As the RMT peripheral exhausts its buffer it sends an interrupt which then refills the buffer just in time. I tried to make the driver fairly generic and re-usable, but it hasn't been thoroughly tested. It currently sets up and manages the RMT directly since...

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  • Adding Analog Support for the Apple II to ninepin

    17 Jul | 16
    • in Electronics • 
    • in Raspberry Pi • 
    • in Apple II • 
    • by Chris Osborn

    Game over man, game over A week ago I was craving some Apple II gaming, but my experience of jittery flakey analog joysticks on the Apple II kind of deterred me. Joystick reading tends to be very sensitive on the Apple II and often the joystick would suddenly jump back and forth between reading up or down. You might be tempted to blame dirty potentiometers, but even back then when the joysticks were brand new this was a problem. The Apple II was originally designed to use paddles as the...

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  • TRS-80 Model I Floppy Repair

    03 Jul | 16
    • in Electronics • 
    • in TRS-80 • 
    • by Chris Osborn

    Another repair project that I’ve had sitting around for quite a while is a TRS-80 floppy drive. It was another “untested” item that I got for a reasonable price off eBay. When it arrived I hooked it up and it didn’t work. A little bit of investigation and I found that the spindle motor wasn’t turning on. Again I got distracted with something else and put the project aside for another time. Precariously balancing I didn’t want to have to test the drive by...

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